The present invention relates to safety devices for power-driven machinery, and more particularly, to a shield for an engraving machine or the like that prohibits the dangerous placement of fingers in the work area of the machine during its operation.
Engraving machines are well-known devices used to stamp or engrave a desired pattern in a piece of material. An engraving machine typically comprises a vertically moving ram carrying a male die. The ram and corresponding die are moveable downward toward a female die mounted on a fixed bed of the machine. A piece of material, such as paper, is placed over the female die by a human operator. The operator then activates the ram and the male die travels vertically downward toward the female die and stamps or engraves the piece of material with a desired symbolic formation, such as letters or numbers. The area at the interface between the male and female dies is termed the "work area" or "break".
After stamping the material, the ram moves vertically upward, thereby moving the male die out of the work area. This allows the machine operator to remove the work piece and insert a new work piece into the work area. The speed of vertical reciprocating movement of the ram, and the amount of time between its movements, can be automatically and adjustably set by the machine operator. Such movements of the ram are always triggered by a clutch arm, which frees the hands of the machine operator to properly position the work piece in the work area.
An inherent problem with engraving machines is that the human operator can inadvertently have his or her fingers in the work area as the vertically moving ram is traveling downward toward the work area. Because these die-stamping engraving machines have existed for decades, history is replete with human operators having fingers mangled or severed by such powerful machinery.
As a result, various shielding devices have been developed to attempt to protect the machine operator from injury. A moveable shield is used to protect the work area from the hands of the operator. The shield is typically operable between an open position in which the operator can access the work area, to a closed position in which it is desirable that it be impossible for the operator the access the work area. The shield must be in front of the work area when in its closed position and offer a small clearance for feeding the work piece over the female die. Yet, at the same time, the shield must protect against the placement of the operator's fingers into the work area when the ram is descending.
It is known in the prior art of shields for engraving machines or the like to utilize various means for moving the shield between the open and closed positions. Such shields are operated pneumatically or hydraulically by the operator activating, for example, a foot pedal. Alternately, the shields may have their movements automatically controlled. It is also known in the prior art to sense when the operator's hands are within the work area and prevent ram movement.
Reznick U.S. Pat. No. 3,186,256 discloses a safety shield comprising two vertical panel sections, the lower section being hinged. The upper section is attached to either an armature of a solenoid or a piston rod. The armature has an associated solenoid, while the piston has a control valve. The panel sections rise up when the press comes down to allow the work piece to bend. When the press is up, the shield is down to restrict access to the contact area of the die portions of the press. Other representative prior shields for engraving or die stamping machines are disclosed in U.S. Pat. Nos. 4,220,032; 3,996,815; 4,488,630; and 4,037,699.
However, in spite of these and other well-known prior art shields, operator injuries have still occurred due to, for example, mechanical or electrical malfunctions, or to intentional or accidental bypassing by the operator of the functioning of the shield. Such malfunctions occur because known prior art shields employ elaborate electrical and/or mechanical schemes for sensing various positions of the shield and the ram and for moving the shield in response thereto.
Heretofore, no known scheme has been implemented wherein movement of the ram directly causes corresponding movement of the shield.
Accordingly, it is a primary object of the present invention to provide a shield for an engraving machine or the like that prevents the machine operator from placing his or her fingers within the work area of the machine during machine operation that could harm the operator.
It is a general object of the present invention to provide a shield for an engraving machine that is moveable away from the work area in response to movement of the ram portion of the machine.
It is another object of the present invention to provide a shield for an engraving machine that is simple in construction and that is easily retrofitted onto existing engraving machines.
The above and other objects and advantages of the present invention will become more readily apparent when the following description is read in conjunction with the accompanying drawings.